Continuous strand pressure impregnator



June 17, 1969 R. C. BRYAN CONTINUOUS STRAND PRESSURE IMPREGNATOR Filed Oct. 9, 1967 INVENTOR L RICHARD c. BRYAN ATTORNEY United States Patent 3,450,094 CONTINUOUS STRAND PRESSURE IMPREGNATOR Richard C. Bryan, Fairhaven, Mass., assiguor to Crompton & Knowles Corporation, Worcester, Mass., a corporation of Massachusetts Filed Oct. 9, 1967, Ser. No. 673,689 Int. Cl. B 11/00; B05c 3/02 U.S. Cl. 118-10 Claims ABSTRACT OF THE DISCLOSURE This invention relates to coating and impregnating apparatus, and more particularly to apparatus for coating and impregnating strands of textile filaments with impregnating fluid.

The invention is particularly adapted for coating and pressure impregnating continuous strands or bundles of glass filaments with a liquid thermosetting resin. The impregnation of the glass fiber strands requires that resin penetrate the strand bundles between individual filaments.

A common method of coating and impregnating glass strands is by drawing them through an open tank containing impregnating resin and an orifice of a size to allow the coated strand to pass therethrough with the proper amount of resin. Because of the viscosity and tenacity of the resin, the strands carry the resin forward thus causing a pileup of resin near the orifice. This creates a deficit of resin at the other end of the tank and reduces the effective length of immersion of the strand in the resin. This method also does not create pressure to force resin between filaments. Other systems for impregnating fibrous products are known which make use of conveying tubes to insure suflicient exposure in the impregnating fluid but provide no means to aid the impregnating process with pressure.

It is an object of this invention to provide apparatus which enables continuous filamentary strands to undergo suflicient exposure to an impregnating fluid while controlling the pressure of the fluid.

Another object of the invention is to provide apparatus which enables the fluid which is adhesively dragged by the motion of the textile strands through the impregnating fluid to control the pressure of the fluid.

A more specific object of the invention is to provide means to adjust the pressure of the impregnating fluid.

These objects are accomplished by the provision of one or more impregnator tubes which connects an impregnating fluid filled reservoir to a pressure chamber. The filamentary strands pass through the impregnating fluid in the reservoir through the impregnator tubes and into the pressure chamber thereby adhesively dragging some of the fluid toward the chamber. The strands are drawn from the pressure chamber through an orifice which allows some of the impregnating fluid to pass through the orifice with the strands. The amount of impregnating fluid passing through the orifice in this fashion is less than the amount entering the pressure chamjber ithrough the impregnator tubes. The forward movement of fluid keeps the pressure chamber full and forces the excess fluid back to the reservoir via a return tube, thereby creating pressure in the pressure 3,450,094 Patented June 17, 1969 ice chamber. This pressure, plus the long emersion of the strands in the fluid filled tubes enables the fluid to thoroughly impregnate the strands. The pressure in the chamber can be varied by varying the conditions under which the excess fluid must return to the reservoir. This can be done by restricting the flow of fluid, either by altering the diameters of the impregnator and return tubes or by placing a gate or the like in the tubes. An increase in the angle of the return tube and height of the reservoir will increase the pressure in the chamber. Other variables which affect the pressure of fluid in the chamber are the speed of pull of the filaments, depth of fluid in the reservoir and the viscosity of the fluid. The length of the impregnating tube will aflect the pressure of the fluid in the tube as well as to vary the immersion time of the strands.

The invention, and additional objects and advantages thereof, will be best understood from the following description thereof, when read in conjunction with the accompanying drawings in which:

FIGURE 1 is a longitudinal cross section of the impregnating apparatus with one means of varying the pressure in the pressure chamber;

FIGURE 2 is a vertical section on line 2-2 of FIG- URE 1 showing the impregnator and return tubes in cross section; i

FIGURE 3 is a fragmentary view of the return tube with a modified means of varying the pressure in the pressure chamber; and

FIGURE 4 is a fragmentary view of a portion of the pressure chamber and means to indicate the amount of pressure in the chamber.

Referring to FIGURES l and 2, the impregnating apparatus is generally indicated by the reference numeral 10. This apparatus has a reservoir 12 in which is maintained a supply of impregnating fluid such as resin. This fluid is indicated by the reference character R. A pressure chamber 14 is spaced from the reservoir and is connected thereto by impregnating tubes 16.

One end of each of the impregnating tubes 16 opens at 18 into the reservoir near the bottom thereof. The other ends of the tubes 16 open at 20 into the pressure chamber. The tubes are shown at a slight upward angle from the reservoir to the pressure chamber to increase the drag of the impregnating fluid on the strands, but this is not essential for the operation of the apparatus. One end of a return tube 22 is connected to an overflow opening 24 in pressure chamber 14 and the other end to an opening 26 in reservoir 12.

The filamentary strands F to be impregnated enter the reservoir from a supply source (not shown) over guiding grooves 28 in the rounded edge 30 of the reservoir. The strands are then trained around a guide or roll 32 near the bottom of the reservoir and are pulled through the impregnator tubes 18 into the pressure chamber 14 and then out through an outlet orifice 34 to either be collected on a beam 36 or for immediate use. Beam 36 can be driven by any conventional drive means much as v a motor 38.

As the strands are pulled through the reservoir they adhesively drag some of the impregnating fluid into the impregnator tubes and then into the pressure chamber. The amount of fluid drawn through the impregnator tubes 16 from the reservoir to the pressure chamber exceeds the amount of fluid leaving through orifice 34 with the strands F. The continued influx of fluid into the chamber keeps it full and maintains the pressure of the fluid therein. The excess amount of fluid is forced back to the reservoir through return tube 22 by the continued influx of fluid from the impregnator tubes 16. The impregnator tubes enable the strands to be submerged in the impregnating fluid for a sutficient length of time and the pressure chamber provides the necessary pressure for impregnation of the strands. As the strands move through the impregnator tubes, they are subjected to an increasing amount of pressure therein due to the resistance of the fluid in the pressure chamber and the continued flow of fluid from the reservoir. This provides for gradual and uniform impregnation of the strands.

Return tube 22 is shown at a slight uphill angle from the pressure chamber to the reservoir. The greater the angle of the return tube, the more pressure that is required to move the fluid therethrough. The greater the pressure that is required to move the impregnating fluid through the return tube, the greater the pressure that will be created in the pressure chamber and the impregnator tubes. This pressure can also be increased by restricting the flow of fluid through the return tube. For example, a return tube having a smaller internal diameter could be used. One convenient way of restricting the flow of fluid is to provide an adjustable gate 40 at the point where the return tube 22 opens into the reservoir at 26. Gate 40 is shown mounted near the upper edge of the inner wall 42 of the reservoir by bolts 44. Slots 46 in wall 42 of the reservoir allow the gate 40 to be adjusted vertically. By loosening bolts 44, gate 40 can be adjusted so that the bottom edge 48 of the gate will block as much of opening 26 as is necessary to restrict the return flow of impregnating fluid through return tube 22. The amount of blockage will be determined by the amount of pressure that it is desired to be maintained in chamber 14. Once the desired setting is achieved, bolts 44 can be tightened.

Referring to FIGURE 3, there is shown a modification of flow restricting means. In this case, an adjustable pressure valve 50 is installed on the return tube. Valve 50 can be of any commercial type which will restrict the flow of material therethrough and which can be adjusted by a turn screw or the like 52.

Referring to FIGURE 4, there is shown a calibrated transparent measuring tube 54 which is inserted into the pressure chamber 14 for measuring the pressure therein. The impregnating fluid will rise into the measuring tube to a height which will vary with the pressure. The calibrations can be arranged so that pressure can be read directly from the tube if it is so desired.

In this way, fine adjustments can be made in the flow restricting means such as valve 50 or gate 40 while reading the pressure from tube 54.

The invention is particularly useful for impregnating strands of glass filaments with resin but it may also be used for other types of fiber or filamentary strands which require impregnation with other types of impregnating fluid. The invention provides for lengthy emersion of strands in impregnating fluid under pressure. It is contemplated therefore that the invention can be used for a large range of continuous filamentary strand impregnation problems. It is also contemplated that the pressure can be adjusted in several difierent ways, other than the example shown, by those skilled in the art.

What is claimed is:

1. An apparatus for pressure impregnating strands of filamentary material, comprising, in combination:

(a) a reservoir adapted to contain an impregnator (b) a pressure chamber having an orifice outlet;

(c) at least one impregnator tube connecting said reservoir and said chamber;

(d) means for directing said strands through said reservoir and impregnating fluid contained therein, said impregnator tube, said pressure chamber and said orifice; and

(e) means for controlling the pressure of said fluid within said chamber and impregnator tube, whereby said strands are uniformly impregnated.

2. The apparatus set forth in claim 1 wherein said impregnator tube is inclined upwardly toward said pressure chamber.

3. The apparatus set forth in claim 1 wherein said means for controlling the pressure of said fluid within said chamber comprises a controlled overflow opening from said chamber.

4. The apparatus set forth in claim 3 wherein the cross sectional area of said outlet orifice is less than the internal cross sectional area of said impregnator tube, whereby the motion of said strands through said impregnator tube adhesively drags an amount of said impregnator fluid from said reservoir into said pressure chamber in excess of the amount that can pass through said outlet orifice with said strands to maintain the pressure in said chamber and impregnator tube.

5. The apparatus set forth in claim 3 further comprising a return tube connecting said overflow opening to said reservoir, whereby excess fluid is returned to said reservoir.

6. The apparatus set forth in claim 5 wherein said return tube is located on a higher plane than said impregnator tube, and is connected to said reservoir above the level of fluid in the reservoir.

7. The apparatus set forth in claim 5 further comprising adjustable flow restricting means for said return tube, whereby the flow of impregnating fluid from said pressure chamber to said reservoir can be restricted to vary the pressure in said pressure chamber.

8. The apparatus set forth in claim 7 wherein said adjustable means is a battle plate slidably mounted adjacent the opening of said return tube into said reservoir, whereby the size of said opening can be varied to vary the flow of impregnating fluid.

9. The apparatus set forth in claim 7 wherein said adjustable means is a pressure valve located between the ends of said return tube, whereby the flow of impregnating fluid through said return tube can be varied to maintain a predetermined pressure reading.

10. The apparatus set forth in claim 1 further comprising a calibrated transparent tube opening into said pressure chamber, whereby the pressure in said chamber can be measured.

' References Cited WALTER A. SCHEEL, Primary Examiner.

I. P. MCINTOSH, Assistant Examiner.

US. Cl. X.R. 68-175; 118-405 

